Image Resizer Online Free
Resize images by exact pixel dimensions or percentage. Lock aspect ratio to prevent distortion, choose output format, and download the result instantly. No upload to any server — runs entirely in your browser.
⏱ 6 min read · Complete guide below
Drop an image here or click to browse
JPEG, PNG, WebP, GIF, BMP
How to Resize an Image
- 1Drop your image onto the upload area or click to browse for a file (JPEG, PNG, WebP, GIF, BMP).
- 2Choose By Dimensions to enter exact pixel sizes, or By Percentage to scale proportionally.
- 3Select an output format and quality level, then click Resize Image.
- 4Click Download to save the resized image to your device.
When to Use Each Output Format
JPEG is the best choice for photographs — it offers small file sizes with adjustable quality. PNG is lossless and supports transparency, making it ideal for logos, icons, and screenshots. WebP is a modern format that offers better compression than JPEG at equivalent quality and is supported by all modern browsers.
Resizing vs Compressing vs Cropping
These three operations are often confused but do different things. Resizing changes the pixel dimensions of an image — a 4000×3000 photo becomes 800×600, for example — which also reduces file size as a side effect. Compressing keeps the dimensions the same but reduces file size by lowering quality or using a more efficient format. Cropping removes part of the image entirely, changing its composition and shape. This tool focuses on resizing, with format and quality controls that let you compress at the same time. If you only need a smaller file at the same dimensions, lower the JPEG quality; if you need a different shape, crop first, then resize.
How to Resize Without Losing Quality
The most important rule is to downscale, not upscale. Making an image smaller discards pixels and generally looks clean, but making it larger forces the software to invent detail that was never captured, producing a soft, blocky result. Always start from the highest-resolution original you have. When you must reduce size, resize to the exact dimensions you will actually display rather than something larger that the browser then shrinks — this both sharpens the result and speeds up your page. For photographs, keeping JPEG quality around 80–90% preserves detail while cutting file size dramatically; going above 95% rarely looks better but inflates the file.
Resizing for Web Performance
Oversized images are one of the most common causes of slow web pages. A photo straight from a phone can be 4000 pixels wide and several megabytes, yet it might be displayed in a 600-pixel column — meaning the visitor downloads many times more data than they can even see. Resizing images to their displayed size before uploading, and choosing an efficient format like WebP, can cut page weight by 80% or more, which improves load times, mobile data usage, and search rankings. Because this tool runs entirely in your browser with no upload, you can prepare correctly sized images privately and instantly, even in bulk.
What Actually Happens When You Resize
Resizing is not as simple as adding or removing pixels — the software has to resample the image, calculating new pixel values from the old ones. When you downscale, several source pixels are averaged together into each new pixel, which is why reduction usually looks smooth and clean. When you upscale, the reverse happens: there are more output pixels than real data, so the software interpolates between existing pixels to guess the values in between. That guessing is what makes enlarged images look soft or blurry, and no ordinary resizer can add detail that the camera never captured. This is the technical reason behind the golden rule of resizing: always work down from the largest original you have. If you routinely need a small version, keep the full-resolution master file and resize a copy, so you never have to enlarge a shrunken image later.
Image Resizing Tips
Common Social Media Sizes
Twitter profile: 400×400px. Instagram post: 1080×1080px. Facebook cover: 820×312px. LinkedIn profile: 400×400px. Use the dimensions mode for exact targets.
Retina Display
For screens with 2x pixel density (Retina, HiDPI), create images at 2x the display size. A 200×200 display image should be 400×400px in the source file.
Web Performance
Serving images at their displayed size rather than relying on CSS to scale them down significantly improves page load speed. Use the percentage mode to scale by 50% for a quick optimization.
JPEG Quality
For web use, JPEG quality of 75–85% typically offers a good balance between file size and visual quality. Quality above 90% gives diminishing returns with much larger file sizes.
Frequently Asked Questions
Does resizing an image reduce quality?
Upscaling (making an image larger than the original) always reduces quality since it requires inventing pixel data that does not exist. Downscaling generally preserves quality well. For JPEG output, higher quality settings (80–95%) minimize compression artifacts.
Is my image uploaded to a server?
No. The entire resizing process happens in your browser using the HTML5 Canvas API. Your image never leaves your device.
What formats can I output?
You can output JPEG (with adjustable quality), PNG (lossless), or WebP (modern format with excellent compression). JPEG is best for photographs; PNG for graphics with transparency; WebP for web delivery where browser support allows.
What does "lock aspect ratio" do?
When enabled, changing the width automatically adjusts the height proportionally (and vice versa) so the image is not distorted. Disable it to set arbitrary dimensions that may stretch the image.
What is the maximum image size?
The browser's Canvas API can handle very large images, but performance depends on available memory. For images over 20 megapixels, you may experience slower processing. The tool works best with images up to about 4000×4000 pixels.
How do I resize an image to a specific file size, like under 100 KB?
File size depends on both dimensions and quality, so use them together. First reduce the pixel dimensions to what you actually need, then, for JPEG or WebP output, lower the quality setting and watch the resulting file size. Dropping quality to around 70–80% often brings a photo well under common limits with little visible loss. If it is still too large, reduce the dimensions further — halving the width and height cuts the pixel count to a quarter.
Will resizing crop the image or change its shape?
No. Resizing scales the whole image; it does not remove any part of it. With "lock aspect ratio" enabled, the proportions are preserved so nothing is stretched or cut off. If you need to change the shape or remove part of the picture, use a cropping tool first and then resize the cropped result here.
Does resizing remove EXIF data like location and camera info?
Yes. Because the image is redrawn through the browser's canvas, the output is a fresh file that does not carry over the original EXIF metadata — including GPS location, camera model, and timestamps. This is a useful privacy side effect: resizing a photo before sharing it strips potentially sensitive location data along the way.
Can I resize transparent PNGs without a black or white background?
Yes — choose PNG or WebP as the output format and transparency is preserved. Only JPEG lacks an alpha channel, so exporting a transparent image as JPEG will fill the transparent areas with a solid colour. For logos, icons, and any graphic that needs to sit on different backgrounds, keep the output as PNG or WebP.